Blindness has a major impact on patients and their families life. Degeneration of photoreceptors due to age macular degeneration and retinitis pigmentosa is a major reason for blindness. A wide variety of strategies including drug injections, stem cells, optogenetics, gene therapy are promising strategies to recover the loss of the photoreceptor cells, but currently, they have significant limitations. Instead, electronic retinal implants, the most mature solution, made significant progress towards aiding large object recognition for blind patients. However, nowadays the production of clinically approved implants of Argus II and Alpha AMS was discontinued due to the unmet expectations of quality of vision (i.e. below legal blindness level in terms of visual acuity and field of view).
Alternatively, retina implants using photovoltaic conversion of light to electricity show high promise for high-quality artificial vision. Photovoltaic retina implant based on silicon is currently under clinical investigation and it demonstrated significant benefits for surgical simplicity and potential for high-resolution artificial vision. Photovoltaic retina implant based on conventional inorganic silicon photodiodes has the advantage of having a high-level charge injection efficiency for cell stimulation, but they are rigid, thick (~30 µm) and have challenges for miniaturization of tandem photodiodes. Conversely, there are also organic photodiodes based polymeric implants that are soft, thin (<1 µm) and can be miniaturized via vertical-stacking of tandem photodiodes, but their charge injection efficiency is significantly lower than silicon. Therefore, there is an urgent need for retinal implants that can simultaneously operate with high efficiency like silicon and can be fabricated via the use of solution-based fabrication technique for large-area, high-resolution and flexible retinal implants.
Toward this aim, we develop efficient, thin, and cellular-sized photovoltaic neural interfaces based on quantum dots and nanowires. For that, non-toxic quantum dots that have strong light absorption at near-infrared are synergized with the nanowires that have unique light-trapping and high surface area for efficient photostimulation of neurons. Then, we translate these devices to porous and flexible tissue-like retinal implants for artificial vision. Starting from the nanomaterial synthesis to optoelectronic device fabrication and bioelectronic mesh formation, this challenging innovation combining nanomaterials, photonics and abiotic-biotic interfaces are explored from primary neurons up to in-vivo experimental models of photoreceptor degeneration in order to move the results toward clinical application.
